Alarm signal box



2 Sheets-Sheet 1 Filed March 22, 1949 Ema- I...

m H m M m I. m m 4 4 4 2 M y 1951 J. I. ELLMANN 2,553,244

ALARM SIGNAL BOX Filed March 22, 1949 2 Sheets-Sheet 2 INVENTOR. Jr/r J.ta'amxwwv Patented May 15, 1951 UNITED STATES FATENT OFFICE ALARM SIGNALBOX Jack I. Ellmann, Washington, D. 0.

Application March 22, 1949, Serial No. 82,881

3 Claims. i

This invention relates to alarm signal boxes and has more particularreference to signal boxes of the so-called break-glass type, such as areemployed, for example, in fire or other alarm systems.

One object of the present invention is to provide a novel and improvedalarm signal box of the above type having a hinged hammer adapted tosmash the glass into fragments concentrically around the switch forpositive release thereof and simultaneously prevent glass fragments fromflying out of the box.

Another object of the invention is to provide an alarm signal box, asabove characterized, having means for carrying a spare glass to replacea smashed glass.

Another object of the invention is to provide an alarm signal box, asabove characterized, having means to permit testing of the alarm systemwithout breaking the glass or completely opening the box.

Another object of the invention is to provide an alarm signal box, asabove characterized, having means for preventing the glass from fallingout when the box is opened for glass replacement.

Another object of the invention is to provide an alarm signal box, asabove characterized, in which the glass is resiliently held in its frameso that it will have sufficient give to prevent shattering by the hammerwhen the only force exerted by the hammer is due to its own weight.

A further object of the invention is to provide a simple, inexpensive,rugged signal box which is efiicient and safe in operation, and onewhich is quickly and easily assembled and installed.

Other objects and advantages of the invention will appear in thefollowing specification when considered in conjunction with theaccompanying drawings, wherein:

Fig. 1 is a perspective view of a preferred form of an alarm signal boxconstructed in accordance with the present invention;

Fig. 2 is a vertical sectional view taken on the line 22 of Fig. 1;

Fig. 3 is a plan view, with parts broken away, of the mounting plate ofthe box shown in Fig. 1;

Fig. 4 is a plan view with parts broken away, of the under side of thecover plate and hammer of the box shown in Fig. 1;

Fig. 5 is a fragmentary view showing the relative positions of thebreak-glass, break points, and switch, when the alarm box cover isclosed and the alarm is ready to be operated;

Fig. 6 is a view similar to Fig. 5, but showing is hinged to the bottomof the mounting plate;

and

Fig. 8 is a fragmentary perspective view of a.

modified form of mounting plate having a spare glass holder frame formedintegral therewith.

Referring now to the drawings, there is shown in Figs. 1 to 6,inclusive, one modification of an alarm signal box constructed inaccordance with the present invention and comprising a mounting platel6; 2. cover plate H, a hammer i2; and a switch mechanism [3.

The mounting plate It; is shown as a generally fiat, rectangular plateof cast metal having a spaced pair of upstanding apertured lugs l3, itformed integral therewith on its upper end. The plate is shown as beingprovided with a pair v.of oblong openings i5, it which receive thescrews by means of which the plate is attached to a wall or a switchbox, and a circular opening ii in which the switch mechanism [3 ismounted.

A pair of upstanding lugs ii are formed integral with the plate Hi andpositioned in substantially horizontal alignment with the circularopening IT. The upper portions of the lugs have rectangular recesses i9formed therein which form supports for a spare glass 2%. An upstandinglug 2| positioned above the lugs 18- and adjacent the left hand edge ofthe plate It, as viewed in Fig. 3, forms a stop for the spare glass.

The cover plate H is shown as a hollow-like cast metal member having afiat front wall 22 merging into rounded top and bottom walls 23, at andhaving vertical side walls 25, 25. The plate I l is provided with aspaced pair of integral apertured lugs 21, '28 projecting forwardly andupwardly from its upper edge (see Fig. 1). The front wall 22 of theplate Ii has a rectangular opening 29 formed therein, the edges of whichform a frame for a rectangular frangible plate 39 mounted on the insideof the cover plate. The plate 30 may be made of any suitable frangiblematerial; preferably, and as shown, the plate is made of glass. Theglass plate '36 is supported on the inside of the cover plate it bymeans of a spaced pair of integrally formed inwardly and upwardlyextending tongues El, 32. The space between the upwardly extendingportions of the tongues and the rear surface of the front wall of theplate forms recesses 33, 3:2 in which the bottom edge portion of theglass plate 33 is received.

The hammer I2 is shown as a flat, generally rectangular plate of castmetal having a spaced pair of rearwardly projecting apertured lugs 35,36 formed integral therewith along its upper end. The hammer is made ofa width greater than the width of the rectangular opening 29 in thecover membe H to prevent glass splinters from flying out of the openingwhen the hammer is used to shatter the glass plate 36.

An integral inwardly projecting cylindrical lug 31 formed on the rearsurface of the hammer provides a striking head. The outer end of the lug31 has a rounded concavity 38 formed therein with the circular edge ofthe concavity serrated as indicated at 39.

The switch mechanism l3 in the particular embodiment shown issubstantially identical in construction to that shown in U. S. PatentNo. 1,883,786, issued October 13, 1932, to H. C. Housen et al., for aPush Switch, and comprises a laminated insulating base 4% containingsuitable contacts to which the electrical circuit wires 4!, 32 areattached; a metal casing 33 embracing the insulating base and having anopening in its top; an externally threaded sleeve 45. secured in theopening in the casing; a hollow cylindrical plunger :55 slidably mountedwithin the sleeve;

and a button 46 slidably mounted in the plunger The switch is mounted onthe rear of the mounting plate with the threaded sleeve l4 projectingthrough the circular opening I! and held in place by means of lock nuts*1? and 48. Proferably, and shown, t1 e threaded sleeve 44 is providedwith a longitudinal keyway slot =13 in which is received a keyway lug5i? projecting from the mounting plate into the circular opening ii toprevent the switch from turning.

As shownin Figs. 1 and 2, the mounting plate Hi, the cover plate ll, andthe hammer [2 are hingedly connected together by a rod 5% extendingthrough the horizontally aligned apertured lugs formed on the tops ofthese members.

The lugs on the cover plate are tioned to the outer walls of the lugs onthe mounting plate and the spaced lugs on the hammer are positioned toengage the inner walls of the on the mounting plate, thereby preventingany lateral inoven :nt of these members relative to each other on therod l.

Prefers ly, and as shown s. l and 2, the height and width of the coverplate is he same as that of the mounting plate, so that when the coverplate is resting on mounting plate, their respective top, bottom andside walls will be flush with each other. The cover plate is heldsecured in its closed position on the mounting plate as shown in Figs. 1and 2, by means of a Philips head screw 52 extending through acountersunk opening in the cover plate and threaded into a screw holeextending through the mounting plate.

The depth oi the side walls of the cover plate is such that when thecover plate is in closed position with the glass plate 39 held pressedagainst the window frame, there will be a slight space between the glassand the tops oi the lugs The switch mechanism i3 is adjustably securedon the mounting plate so that the plunger 65, when in its depressedposition, as shown in Fig. 2, will be slightly below the tips of thelugs 3 with the button 48 in a se:r.-i--depressed position and engagingthe glass as to hold it against its frame. This construction permits aslight "give to the glass plate. When first struck by the hammer, theglass plate will press the button 46 inwardly until the glass platerests against the tips of the lugs it, where continued inward movementof the hammer shatters the plate (see Figs. 5 and 6). This resilientmounting of the glass plate provides suficient give to permit the hammerto fall from its highest raised position against the glass withoutbreaking it. This is true even when the glass plate is made of ordinarywindow glass. In this connection, it should be pointed out that therecesses 33, 34 in which the lower edge portion of the glass plate restsis made of sufficient width to take care of the inward movement of theglass. If desired, and as shown in Fig. 2 the inner surface of theupwardly extending portion of the glass holding tongues 3 i 32 may bepositioned to lie in the same vertical plane witlrthe tips of the lugs18 so that the tongues 3|, 32 will act as break points along with thelugs 8.

The striker head or lug 3'? of the hammer is so positioned thereon thatwhen the hammer is moved to break the glass plate the cylindricalstriker head will be concentric with the plunger l5 and, due to theconcavity in the head and the resiliency of the push button 46, thebreaking impact of the hammer on the glass will not damage the switchand, after the glass has been shattered, the striker head will not hitthe switch as the push button 45 will be received in the concavity inthe head. (see Fig. 1). Also, due to the serrated circular edge the headstriking the lass directly 1' the itch in a concentric circle, the glassall around the switch breaks into fragments which drop out of the way ofthe switch tip and permit it to function freely. The serrated edgeprovides a plurality of breaking tips, thereby concentrating the forceof impact at a plurality of points of small area, making the hammer"lOljE-l effective and causing glass to ULJe break into small fragmentsrather than splintering. Experience has shown that splinters Sometimesengage the switch tip and hold it down, preventing it from sounding thealarm.

When the mounting plate it, cover plate H and hammer 52 are assembledtogether and the Philips head screw tightened to hold the cover plateagainst the mounting plate, the glass plate 30 exerts sufficientpressure against the tip of the switch to cause its electrical contactto reverse and hold this position until disturbed, either by thebreaking of the glass 01' by unscrewing the Philips screw. The switchoperates in the same manner as that shown in the aforesaid patent toHousen et al. and is mounted in one line of the electric circuit of thealarm system so that when the switch tip is held pressed inwardly by theglass plate 3f the circuit is opened, and when the glass plate is brokento permit the switch to be resiliently pressed outwardly, the circuit isclosed. In this connection, it should be pointed out that the Philipshead screw which holds the cover plate against the mounting plate,affords a ready means for testing the alarm system without breaking theglass or opening the signal box. The testing is accomplished byloosening the Philips head screw a suflicient number of turns to permitthe cover plate to release the pressure on the switch tip and permit itto be resiliently pressed outward a distance sufficient to close thecircuit and sound the alarm.

In Figure '7, there is shown another modification of an alarm signal boxconstructed in accordance with the present invention. This modificationdifiers from that shown in Figs. 1 to 6,

inclusive, in that the mounting plate I9 is provided with a spaced pairof apertured lugs l3, l4 along its upper edge and a spaced pair ofintegral apertured lugs 53, 54 at its bottom edge; the cover plate i lis provided with a spaced pair of apertured lugs El, 23 at its bottomedge and is hingedly attached. to the mounting plate by a pin passingthrough the apertured lugs at the bottom of the two plates. The hammeri2 is provided with a spaced pair of apertured lugs 556' along its upperedge and is hingedly mounted on the cover plate by a pin 59 passingthrough the apertured lugs at the tops of the two plates. Other than theforegoing, the construction of the three plates and the manner in whichthe signal box operates are similar to the construction and operation ofthe corresponding parts shown in Figs. 1 to 6, inclusive.

In Fig. 8, there is shown a third modification of an alarm box signalconstructed in accordance with the present invention. In thismodification, the mounting plate lil; cover plate ii"; and hammer i2 aregenerally similar in construction and are mounted in the same manner asthe corresponding parts in the modification shown in Figs. 1 to 6,inclusive, except that the mounting plate ill is provided with anintegrally formed spare glass container til at its upper end.

The spare glass container 5'1 is shown in the form of an open toprectangular box-like memher having a cover plate 58 secured thereto, asby means of a bolt 59 and a screw 69. To remove the cover plate 58, thescrew Ed is unscrewed from the container and the cover plate swung tothe right about the bolt 59 as a pivot, as shown in Fig. 8. A peep hole6! is provided in the cover plate.

In the modification shown in Fig. 8, the provision of the spare glassholding means on the inat side of the box, as shown in Figs. 1 to 6,inclusive, is optional.

From the foregoing, it readily will be seen that there has been provideda novel and improved alarm signal box of the break-glass type which issimple and rugged in construction, involving only three cast metalmovable parts hingedly connected together and forming a housing for theswitch tip; one which is efiicient and safe in operation, mounted toinsure against accidental breakage, and the hammer being adapted tosmash the glass into fragments concentrically around the switch forpositive release thereof and simultaneously prevent glass fragments fromflying out of the box; one which permits testing of the alarm systemwithout breaking the glass or completely opening the box; and one whichprovides a housing for a replacement glass plate.

Obviously, the invention is not restricted to the particular embodimentsthereof herein shown and described.

What is claimed is:

1. An alarm station comprising a mounting plate having a spaced pair ofupstanding projections formed thereon to provide breaker points; switchmechanism carried by said mounting plate, said switch mechanism having'a tip portion spring biased to an extended position to close the theglass plate being resiliently;

Elf:

switch and movable to a retracted position to open the switch, saidswitch tip portion being positioned between said upstanding projections;hollow cover plate hingedly connected at one end to said mounting plateto form a switch box and having an opening therein covered by areplaceable plate of frangible material, said opening being positionedso that, when said cover plate is closed, said frangible plate willengage said switch tip and hold it in its retracted position; and ahammer member hingedly connected to the switch box in front of saidcover plate and having striking head positioned to engage said frangibleplate and shatter it against said breaker points when the hammer isstruck a blow, said striking head being provided with a rounded recessin its outer end normally aligned concentrically with said tip portionof said switch mechanism.

2. An alarm signal box, as set forth in claim 1, wherein the peripheralwall of the rounded recess in the striking head of said hammer isserrated to shatter the glass around the switch tip without striking thetip after the glass is broken.

3. An alarm station comprising a mounting plate having a spaced pair ofupstanding projection formed thereon to provide breaker points, saidprojections being provided with top opening recesses; switch mechanismcarried by said mounting plate, said switch mechanism having a tipportion spring biased to an extended position to close the switch andmovable to a retracted position to open the switch, said switch tipportion being positioned between and in horizontal alignment with saidupstanding projections; a hollow cover plate hingedly connected at oneend to said mounting plate to form a switch box and having an openingtherein covered by a replaceable plate of frangible material, saidopening being positioned so that, when said cover plate is closed, saidfrangible plate will engage said switch tip and hold it in its retractedposition; a hammer member hingedly connected to the switch box in frontof said cover plate and having a striking head positioned to engage saidfrangible plate and shatter it against said breaker points when thehammer is struck a blow; and a. spare frangible plate mounted on saidmounting plate with its bottom edge engaged in the recesses formed insaid upstanding projections.

JACK I. ELLMANN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,345,457 Olson July 6, 19201,479,608 Jackson Jan. 1, 1924 2,014,861 Neely Sept. 1'7, 1935 2,083,324Edwards June 8, 1937 2,448,330 Sperzel Aug. 31, 1948 OTHER REFERENCESData Sheet No. 32160, Fire Alarm Station Type NC Faraday by Stanley andPatterson, Boston, Mass, dated Mar. 26, 1946.

